Last call for loss of mains protection funding

Electricity networks have issued a last call for distributed generators to apply for funding to update or upgrade their loss of mains protections to comply with new regulatory requirements coming into effect on 1 September.

The funding is part of the Accelerated Loss of Mains Change Programme being run by National Grid Electricity System Operator and distribution network operators (DNOs).

The new requirements have been introduced through a modification to the Distribution Code and stipulate that vector shift loss of mains protections must be removed and/or replaced with rate of change of frequency (RoCoF) protections. Meanwhile, generators with RoCoF protections set to less than 0.5Hz/s must increase the cut off to the new limit of 1Hz/s with a definite time delay of 500 milliseconds.

Similar requirements are already in place for some distributed generators, having been brought in incrementally through a series of earlier code modifications.

The ESO is currently required to limit the rate of change of frequency on the electricity system to 0.125Hz/s to prevent generators with RoCoF protections from inadvertently tripping. This task has become increasingly challenging and costly as the proliferation of asynchronous renewables and the closure of synchronous conventional generators such as coal and gas plants make the power grid more susceptible to sudden changes in frequency.

Nuisance tripping by distributed generators with overly sensitive loss of mains protections was a major contributor to the blackout in August 2019 that left millions of customers without power.

The ESO says the introduction of higher RoCoF limits will bring a significant reduction in balancing costs.

The Accelerated Loss of Mains Change Programme was launched in September 2019 to provide funding to eligible generators to make the necessary upgrades or updates to maintain compliance with the Distribution Code.

The funding is on offer to distributed generators that were installed before February 2018 (or in some cases July 2018), have a capacity of between 11kW and 50MW (or between 3.68kW and 50MW for single-phase generators) and are connected via the G59 engineering requirement of the Distribution Code.

The equipment changes concern the inverters, converters or G59 relays that are responsible for loss of mains protection settings.

With the deadline set for 10 May 2022, eligible generators now have less than four weeks left to apply for funding under the programme. The ESO noted that once the funding ends, generators will still need to meet the new requirements but will have to pay for the necessary changes themselves.

Cheng Chen, senior manager for the Accelerated Loss of Mains Change Programme at the ESO, said: “Compliance with Loss of Mains requirements is not optional and so electricity generator owners should take advantage of the funding that is available now to help them make the upgrades.”

It also warned that non-compliance with the new requirements will pose a risk to the operation of the electricity system and that generators which fail to meet them could be subject to enforcement action, including de-energisation of their whole site.

“This is a relatively small change for most generator owners to make, but if we can achieve widespread compliance the combined impact will have a huge benefit to our electricity network,” Chen added.

“By becoming compliant, generator owners will be futureproofing their power and helping to deliver a strong, resilient, and low carbon electricity network to protect our power for future generations.”